double yolks, is this normal?

My black star hen starting laying eggs about a month ago and she has pretty much given me an egg a day. This past week she has been laying giant, double-yolk eggs. I mean they are huge! Its actually really cool, but I was just wondering if this is normal? And is this healthy for her body?

I would say it's normal for her breed. (I am what I would call new to chickens) I know when I buy my fresh eggs from the farm down the road the RIRs and the black sex links seems to lay a lot of double yolkers. I can't wait for my chickens to be old enough to lay.